If you have multiple IP Address in your string separated by comma ,
then you can do:
string ip = "123.37.71.238,123.37.71.239";
List<IPAddress> ipAddressList = ip.Split(',')
.Select(IPAddress.Parse)
.ToList();
If you want to use IPAddress.TryParse
then you can do:
IPAddress tempIP = null;
List<IPAddress> safeList = ip.Split(',')
.Where(r => IPAddress.TryParse(r, out tempIP))
.Select(r => tempIP)
.ToList();